Dr Thermal TI-R8639L

Light performance, low noise — Joe

SUMMARY: Not for aggressive P4 cooling, although relatively quiet.

Dr Thermal was nice enough to send a sample of their Dr Thermal TI-R8639L P4 heatsink. This is an aluminum radial fin design made by extrusion. The base

is flat and fully covers the P4 case; nothing extraordianry.

The fan is an T&T Model #MW-715H12C – a 70 x 15mm unit rated at 33 cfm @ 3800 rpm (this sample ran at 4050 rpm). I found it to be tolerably quiet – I measured its noise at 58 dBA with a Radio Shack sound meter 8″ from the fan’s intake, substantially less than a Delta 38 (about 69 dBA); Dr Thermal specs the noise at 34 dBA. It consumes about 5 watts, so it should be OK to use a motherboard fan header.

Mounting is its best feature – with the lever in the “up” position, engage the retention base; then swing the clip closed and it’s firmly mounted – easy, simple and very effective.

In summary, a fairly conventional aluminum extrusion heatsink with a very secure and easy to use clip.

The TI-R8639L was first tested on the CPU Die Simulator which gives results that are unaffected by motherboard influences. I then tested it on a Lucky Star P4A845D with a modified P4 1500 to read CPU case temps, as an example of what users might see on their systems.

Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

Motherboard results place the TI-R8639L in the lower rank of heatsinks (Heatsink Ranking).

Not for aggressive P4 cooling, although relatively quiet.

Thanks again to Dr Thermal for sending this our way.

Email Joe